1. Field of the Invention
This invention relates to a tape cassette, and more particularly, to a pressure flap held in a cassette housing for resiliently contacting the running tape and minimizing slackening thereof.
2. Description of the Prior Art
When a tape cassette is being handled, or is otherwise disengaged from the recording and/or reproducing apparatus with which it is intended to be used, one or both of the freely rotatable tape reels within the cassette housing may turn and slacken the tape, particularly across the opening of the cassette housing.
It is essential for the proper operation of tape cassettes that excessive looseness or slackness in the running tape be avoided, because if the run of the tape is excessively loose or slack, the tape may be improperly engaged by the magnetic head, or may be improperly wound internally of the cassette. In either case, damage to the tape may occur, or defective sound recording or reproducing operations may result.
To compensate for the looseness or slackness, pressure flap assemblies are used to maintain a resilient pressure upon the running tape. Pressure flaps are basically resilient, flexible elements, made preferably of plastic, fixed at one end to the cassette housing and have their other end a free end which resiliently abuts the running tape.
Of course, with the manufacture of pressure flap assemblies, as with the manufacture of most items, the major considerations are cost efficient production of the flap and expeditious, automated assembly of the flap into the cassette housing. Thus, the pressure flap having a design requiring the fewest manufacturing steps, in both production and assembly, and yet efficiently eliminating tape slackness, is preferred.
Traditionally, one end of a tape cassette pressure flap was fixedly mounted in the cassette housing by cement or some other type of adhesive. An example of this type of pressure flap assembly has been proposed in U.S. Pat. No. 3,797,779. However, adhesive pressure flaps are unreliable over a long time period primarily because of the following reasons: the adhesive force deteriorates due to binding problems or aging, and the flap eventually peels-off from the cassette housing; the pressure used to fasten the end portions is usually not consistent from one application to the next; leakage of adhesive from the sides of the end portions to the inside of the cassette causes contamination of the magnetic tape; and the necessarily exact positioning required for the end portions is difficult to achieve and, thus adhesive pressure flaps do not lend themselves to efficient automated machine assembly.
Means were then developed to assemble the pressure flap in the cassette housing without the use of the unreliable adhesives. For example, U.S. Pat. No. 4,290,567 has proposed pressure flaps slidably inserted into special holders in the cassette housing. Various embodiments of pressure flaps are disclosed in this patent wherein, either recesses are formed in the fixed ends of the pressure flap for receiving corresponding projections formed in the holders, or the pressure flaps have projections formed thereon for projecting into corresponding recesses formed in the holders. The pressure flap could not be pulled out because of the recess and projection structure. However, the need to manufacture the special recesses and projections in both the pressure flap and the holder demand a relatively expensive manufacturing procedure, and properly aligning the projections with the recesses necessarily complicates automated assembly.
More recently, it has further been proposed in U.S. Pat. No. 4,304,374, to provide a non-adhesive type pressure flap having a "hollow" fitting portion to entirely surround a cylindrical supporting member. A cassette housing projection is further placed between the supporting member and the free end of the pressure flap to abut the midsection of the flap and to prevent rotation of the flap about the supporting member. The "hollow" can take the cross-sectional shape of either a rectangle or a cylinder.
Although his "hollow" fitting design for a pressure flap eliminates some of the problems inherent in both the earlier typical adhesive flap and the projection/recess design, the rather elaborate stamping, spreading and insertion required to produce and assemble the "hollow" fitting pressure flap assembly disclosed in U.S. Pat. No. 4,403,374 still does not teach a pressure flap assembly capable of the most cost-efficient production nor the most time-efficient automated assembly.